Worcester Greenstar 30Si Compact Combi Boiler [2023 Review]

Looking for a great new boiler to fit into your kitchen cupboard, out of sight and out of mind? The Worcester 30Si Compact combi boiler is an excellent option to consider.

And in our review below, we’ll walk you through the 30Si model in detail, even explaining the cheapest way to get it installed.

But first, the answer to the most frequently asked question we get:

Why Not Save £250 and Buy the 30i Instead?

The 25i and 30i are two of the most popular boilers in the Worcester combi range. For standard 2-4 bedroom semi detached properties needing a combi, they’re also the cheapest.

The biggest difference between the I and Si, is the physical size of the boiler. It takes lots of R&D to fit the same technology into a smaller package, so the 25i is cheaper than the 25Si Compact. Likewise, the 30i is cheaper than the 30Si.

So, why not save some cash?

It all boils down to whether you need to fit your new boiler in a kitchen cupboard or similar small space.

If your answer is yes, you’ll need the Greenstar 30Si Compact over the standard 30i combi boiler.

If your answer is no, you can save money by installing the 30i instead. You can read our review of the 30i here.

Is Worcester Bosch Greenstar 30Si Right for My Property?

The central heating output of the Worcester Greenstar 30Si Compact is 24kW, the same as the 25Si Compact. The main difference between the two is the hot water flow rate. The 25Si only hits 8.9 litres per minute, whereas the 30Si produces a much higher 10.7 litres per minute.

Typically, you’d expect the 25Si to be fitted in small properties such as 1-3 bedroom flats, or a small 2 bedroom terraced. The Worcester Bosch 30Si is going to be fitted in a 3 bedroomed semi, although in some scenarios, it may work in a 4 bed.

It’s important to note that whilst the central heating output of the 30Si is reasonable, the output of combi boilers is limited. In fact, combis are not the ideal boiler type for households with high demand for hot water.

You can use this boiler size calculator to determine whether the Worcester Bosch Greenstar 30Si Compact is the most suitable boiler for your property. Alternatively, you can call a Gas Safe heating engineer to come in and survey your property.

30Si Warranty

We’re big advocates of big warranties. At the end of the day, a boiler manufacturer offering a 2-year warranty on a product is hinting their appliance isn’t going to stand the test of time (*opinion).

You’ll find the price differences between boilers with 2, 5, 7 and 10 years warranty isn’t huge. And, as the boiler itself only makes up around 50% of the overall installation cost, we’d always be heading for boilers with the longest warranty.

That means completely avoiding boilers with a 2-year warranty.

A 5-year warranty term would be our bottom line, with anything higher being preferable.

The Worcester Greenstar Si Compact? Using an accredited installer like Heatable, you’ll get a huge 10-year warranty.

Happy days!

Frost Protection

If you’ve been shopping around and reading reviews of some of the best boilers on the market, you’ll notice a lot of boilers offering “frost protection.”

The Worcester 30Si Compact has something much better than frost protection: the Condensesure Syphon.

Put simply:

Boilers are prone to locking up when temperatures drop below zero. Condensed flue gases freeze in the condense pipe, causing the boiler to shut down. And, that’s going to mean no hot water, no heating, and an expensive emergency repair bill; bad news ☹.

The Condensesure Syphon is designed to keep your boiler operational down to -15°C for a period of up to 48 hours; it’s a feature that’s going to keep your boiler running, rain or shine.

Greenstar Si Compact Efficiency

If your boiler is 10+ years old, there’s a good chance you could be saving large chunks of cash by fitting a new one. As an example, a G-Rated boiler in a semi-detached house could cost around £200 per year more to run when compared to a brand new A-rated equivalent.

A G-Rated boiler is less than 70% efficient. The Greenstar 30Si Compact? It’s got an energy efficiency of 88.5% when it’s running at full tilt. If it’s ticking over at around 30%, that efficiency rating can rise to a massive 99.5%.

So yeah, it’s efficient! Now, that’s going to translate to extra pounds notes in your pocket when you pay your gas bill.

Worcester 30Si Costs

There’s no doubt that Worcester Bosch are up there with the more expensive boilers on the market, comparable in price to brands like Baxi, Potterton, and Vaillant. For a Greenstar 30Si, you can expect to pay around £2,400, including the costs of installing the boiler. And that’s a great deal.

Using Heatable’s boiler size calculator we mentioned above, you can get your own price for the Greenstar Si. It’s worth mentioning that prices will vary depending on what options you choose on the clickable form.

Mind you, all variables being the same, a Greenstar 30i will set you back somewhere around £2,150. So, if you don’t need to tuck your boiler away in a small cupboard, you could save £250 by going for the 30i rather than the Worcester Bosch Greenstar Si Compact.

Cheapest Way to Get a Greenstar Si Compact Installed

For most brands, the best deal on installation prices comes from local installers; big nationals struggle to compete with them on price.

In the case of Worcester boilers, Heatable tend to be the cheapest.

Why? Because they concentrate on technology more than on salespeople, it’s fair to say Heatable get boilers like the Worcester Greenstar 30Si Compact at preferential rates.

Also, since the quote process is completely online, there’s no need for a site visit and a sales person, reducing costs further.

You can get your own quote from Heatable by filling in their anonymous property questionnaire.

Should You Get the 30Si Compact?

If you’re looking for a compact boiler, the Worcester Si range is a good place to start. However, do remember that Worcester also has compact models in their CDi Compact range — be sure to check these boilers out, too.

And if you’re looking for a budget compact option, consider the Baxi 600 — we’ve written about it here.

What’s Next?

Thanks for reading our 30Si Compact review.

Looking for specs? The data sheet for the Worcester Bosch 30Si can be found here.

Still got questions about choosing a boiler? Leave a comment or drop us a line through our contact form; we’ll get back to you as soon as possible.